1. Field of the Invention
The present invention relates to a motor comprising a rotor having laminated cores forming an armature core surrounded with a winding and a permanent magnet field system.
2. Description of the Prior Art
The conventional motors are designed to provide two bearings mounted in such a manner that one bearing is mounted on a body case separately constructed from a rear cover and the other bearing is mounted on said rear cover. Accordingly, it has been extremely difficult to adjust a center line of an opening in the bearing on the body case to a center line of an opening in the bearing on the rear cover, thus involving the difficulty in terms of natural increase in cost required to improve the accuracy of parts. These bearings rotatably support a rotor provided with a commutator, and lubricating oil is poured onto the sliding surface between said bearings and the rotor to prevent friction. However, when lubricating oil is poured onto the supporting portion between the bearings and the rotor, the lubricating oil permeates into the commutator to often impair commutating operation of motor. In order to avoid permeation of lubricating oil into the commutator, therefore, an oil thrower has heretofore been provided outside the commutator. However, in the so-called disc commutator of the type in which a disc-like slip ring is mounted perpendicularly to the periphery of the rotating shaft of the rotor, and a cantilever-spring-like brush is disposed in contact with said slip ring, such provision of the oil thrower member involves the difficulty such that when motor is assembled, the oil thrower member will contact the brush to interrupt the assembling work. For this reason, a so-called cylindrical commutator, which is a commutator somewhat more easily assembled than that of disc commutator, of the type in which a cylindrical plate is disposed so as to cover the periphery of a rotating shaft of the rotor, has been used. However, the provision of the oil thrower also in this case involves the difficulty such that motor is not always easily assembled, and that the thickness in an axial direction of the motor will increase because of the thicknesses of the oil thrower and commutator, thus being incapable of obtaining a compact motor.